1. Field of the Invention
This invention relates to a navigation system for a vehicle by which a route to be taken is displayed on a CRT screen, liquid crystal display, or other display means to navigate the vehicle. More particularly, this invention relates to such a navigation system provided with a route determination process by which a desired route can be determined readily and quickly.
2. Prior Art
Known navigation systems are provided with a screen on which a road map is displayed. In one type of system, a route is determined by pinpointing and thereby inputting intersections consecutively from a starting point to a destination by a cursor on the screen or by means of a light pen. In another type of system, once a starting point and destination are input, the shortest route from the starting point to the destination is automatically determined according to map data previously stored, and indicated on the map displayed on the screen.
These types of navigation systems, however, have the following shortcomings. While affording selection of a desired route, the former type of system requires meticulous manual labor of designating each intersection. On the other hand, the latter type of system also falls short, in spite of its operation facility, because it uses previously stored and not up-dated program data in determining a route. When unexpected repair work is undergoing at an automatically selected route, or when the route the user preferred is not selected, the user has to correct the route, after completion of the automatic route determination, in the same laborious manner as in the former type of system.